The son of a Hawaii doctor accused of trying to kill his wife testified on Tuesday that his father told him that his wife had been cheating on him and that he had “tried to kill her”.

Emile Konig, 19, told jurors that he had received two FaceTime calls from his father, Gerhardt Konig, 47, on the morning of 24 March 2025 – the same day prosecutors allege that Gerhardt attempted to murder his wife, Arielle Konig, 37, during a hike on Oahu’s “Pali Puka” trail.

Emile, who lived with his father, stepmother and two younger half-siblings in Maui at the time, also told jurors that his father told him on FaceTime that he would “not be making it back to Maui” and to “take care of the younger kids and that Ari, my stepmom had been cheating on him and that he tried to kill her”.

“During that call, the next plan that he said was to jump off the cliff,” he said. The prosecutor asked him how he reacted, to which Emile responded: “I told him not to.”

Emile testified for less than an hour and did not look at his father as he walked into the courtroom, according to NBC News.

Prosecutors allege that Gerhardt Konig attacked his wife during a hike for her birthday and that he pushed her toward a cliff. They allege that he then came at her with a syringe, before striking her in the head with a rock multiple times.

Gerhardt Konig, who is an anesthesiologist, pleaded not guilty to second-degree attempted murder. His attorneys argue that he acted in self-defense, and that Arielle had attacked him first.

“This was an unplanned, unanticipated scuffle that happened between a couple,” Gerhardt’s defense attorney, Thomas Otake, said during opening statements, per CNN. The defense has also disputed that he tried to push her off a cliff and that there was no syringe involved.

Emile testified that his father made no mention of acting in self-defense during their call.

Arielle Konig, who testified last week, told jurors that the attack began after her husband asked her to take a photo near the cliff’s edge.

“I didn’t want to get too close to the edge of the cliff,” she testified, adding that he then grabbed her and told her, “I’m so fucking sick of this shit get back over there” before pushing her back toward the edge.

“It was very shocking,” she continued. “So yes, my initial reaction was that he must be kidding.”

Arielle said she realized “he’s not kidding because he’s forcefully moving me towards the edge,” noting that the pair wrestled before she threw herself “on the ground”.

“He’s trying to pull me and drag me and then he gets on top of me,” she said. She claimed that he then pulled out a syringe, which she said that she knocked out of his hand.

After that, she said, Gerhardt Konig picked up a rock and began hitting her in the face and head.

“I just started screaming,” she said. “Because in my mind, he was trying to knock me unconscious to get to to be able to drag me over the edge. I just was screaming then as much as I could.”

She said the attack stopped when nearby hikers said they were calling 911. She heard a woman’s voice say “we’re here, we’re calling 911.” After that, she testified that her husband “kind of froze and knelt back away from me, and I just crawled away really slowly.”

She testified that two women helped her get down to safety. The two women testified earlier in the trial, according to CNN, and said that they had just begun their hike when they heard a woman screaming and saw a man striking a woman with a rock.

Arielle also told the court that several months before the incident, her husband had discovered that she was having an “emotional affair” with a co-worker. She said that they had attended couple’s counseling and appeared to be making progress.